This invention is directed to the field of caliper guiding devices in a disk brake and principally to an improved device for guiding a caliper of the type in which an inverted U type fixed member, which extends over an outer periphery of a brake disk and is provided with wall plates disposed parallel to a front surface and a rear surface of said brake disk, guides and supports a friction pad on a bottom within a concavity formed by cutting out a middle portion along the upper edge of said fixed member, and a caliper body for exerting a hydraulic braking force upon said friction pad is laterally slidably guided within an upper space of said concavity. More essentially, the device according to the present invention provides an arrangement in which corrosion is prevented from gathering on a sliding surface between the fixed member and the caliper body to secure stable and smooth movement of the caliper body.